Interferon-gamma

Interferon, gamma
Interferon gamma, line representation
Identifiers
Symbol(s)	IFNG; IFG; IFI
External IDs	OMIM: 147570 MGI: 107656 Homologene: 55526
Gene ontology Molecular Function: • cytokine activity • interferon-gamma receptor binding • transcription activator activity Cellular Component: • extracellular region • extracellular space Biological Process: • regulation of cell growth • neutrophil apoptosis • inflammatory cell apoptosis • cell motility • cell surface receptor linked signal transduction • cell-cell signaling • response to virus • antigen processing and presentation • neutrophil chemotaxis • unfolded protein response • negative regulation of myelination • defense response to bacterium • positive regulation of chemokine biosynthetic process • positive regulation of interleukin-12 biosynthetic process • positive regulation of MHC class II biosynthetic process • positive regulation of interleukin-6 biosynthetic process • regulation of transcription • positive regulation of transcription, DNA-dependent • positive regulation of isotype switching to IgG isotypes • positive regulation of interleukin-1 beta secretion • regulation of immune response
RNA expression pattern
More reference expression data
Orthologs
	Human	Mouse
Entrez	3458	15978
Ensembl	ENSG00000111537	ENSMUSG00000055170
Uniprot	P01579	Q6TDH0
Refseq	NM_000619 (mRNA) NP_000610 (protein)	NM_008337 (mRNA) NP_032363 (protein)
Location	Chr 12: 66.83 - 66.84 Mb	Chr 10: 117.84 - 117.85 Mb
Pubmed search	[1]	[2]

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [3]

Interferon-gamma (IFN-γ) is a dimerized soluble cytokine that is the only member of the type II class of interferons. This interferon was originally called macrophage-activating factor.

Structure of IFN-γ

The IFN-γ monomer consists of a core of six α-helices and an extended unfolded sequence in the C-terminal region. This is shown in the structural models below. The α-helices in the core of the structure are numbered 1 to 6.

Line and cartoon representation of a IFN-γ monomer

The biologically active dimer is formed by anti-parallel inter-locking of the two monomers as shown below. In the cartoon model, one monomer is shown in red, the other in blue.

Line and cartoon representation of a IFN-γ dimer

The structural models shown above (see protein data bank code 1FG9) are all shortened at their C-termini by 17 amino acids. Full length IFN-γ is 143 amino acids in length, the models are 126 amino acids in length. Affinity for the glycosaminoglycan heparan sulfate resides solely within the deleted sequence of 17 amino acids.

Biological activity

In contrast to interferon-α and interferon-β which can be expressed by all cells, IFN-γ is secreted by Th1 cells, Tc cells, dendritic cells and NK cells. Also known as immune interferon, IFN-γ is the only Type II interferon. It is serologically distinct from Type I interferons and it is acid-labile, while the type I variants are acid-stable.

IFN-γ has antiviral, immunoregulatory, and anti-tumour properties. It alters transcription in up to 30 genes producing a variety of physiological and cellular responses. Amongst the effects are:

• Increase antigen presentation of macrophages.
• Activate and increase lysosome activity in macrophages
• Suppress Th2 cell activity.
• Cause normal cells to express class II MHC molecules
• Promotes adhesion and binding required for leukocyte migration
• Promotes NK cell activity

Activation by IFN-γ is achieved by its interaction with a heterodimeric receptor consisting of IFNGR1 & IFNGR2 (interferon gamma receptors). IFN-γ binding to the receptor activates the JAK-STAT pathway. In addition, IFN-γ activates APCs and promotes Th1 differentiation by upregulating the transcription factor T-bet.

IFN-γ is the hallmark cytokine of Th1 cells (Th2 cells produce IL-4). NK cells and CD8+ cytotoxic T cells also produce IFN-γ. IFN-γ suppresses osteoclast formation by rapidly degrading the RANK adaptor protein TRAF6 in the RANK-RANKL signaling pathway, which otherwise stimulates the production of NFκB.

Therapeutic uses

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Interferon-gamma
Systematic (IUPAC) name
Human interferon gamma-1b
Identifiers
CAS number	82115-62-6 98059-61-1
ATC code	L03AB03
PubChem	?
DrugBank	BTD00017
Chemical data
Formula	C761H1206N214O225S6
Mol. mass	17145.6 g/mol
Pharmacokinetic data
Bioavailability	?
Metabolism	?
Half life	?
Excretion	?
Therapeutic considerations
Pregnancy cat.	?
Legal status
Routes	?

Interferons are used to treat infectious diseases and cancer.

Scientists at the University of California at Berkeley have recently discovered that Diindolylmethane (DIM), a naturally occurring compound found in Brassica vegetables, upon oral consumption, is a direct and potent activator of Interferon-Gamma production and sensitivity within the body leading the way for the study of this compound as an anti-viral, anti-bacterial and anti-cancer therapeutic. As this is a dietary compound found in edible vegetables, this has caused a lot of excitement in the immunology field. This compound has also been shown to synergize with Interferon-Gamma in the expression and potentiation of the MHC-I Complex, leading to its study as a possible adjuvant to Interferon-gamma therapeutic models.

Further reading

• Hall, Steven S. (1997) A Commotion in the Blood. New York, New York: Henry Holt and Company. ISBN 0-8050-5841-9
• Information on Interferon and how it relates to hepatitis c
• Ikeda H, Old LJ, Schreiber RD (2002). "The roles of IFN gamma in protection against tumor development and cancer immunoediting.". Cytokine Growth Factor Rev. 13 (2): 95–109. PMID 11900986.
• Chesler DA, Reiss CS (2003). "The role of IFN-gamma in immune responses to viral infections of the central nervous system.". Cytokine Growth Factor Rev. 13 (6): 441–54. PMID 12401479.
• Dessein A, Kouriba B, Eboumbou C, et al. (2005). "Interleukin-13 in the skin and interferon-gamma in the liver are key players in immune protection in human schistosomiasis.". Immunol. Rev. 201: 180–90. doi:10.1111/j.0105-2896.2004.00195.x. PMID 15361241.
• Joseph AM, Kumar M, Mitra D (2005). "Nef: "necessary and enforcing factor" in HIV infection.". Curr. HIV Res. 3 (1): 87–94. PMID 15638726.
• Copeland KF (2006). "Modulation of HIV-1 transcription by cytokines and chemokines.". Mini reviews in medicinal chemistry 5 (12): 1093–101. PMID 16375755.
• Chiba H, Kojima T, Osanai M, Sawada N (2006). "The significance of interferon-gamma-triggered internalization of tight-junction proteins in inflammatory bowel disease.". Sci. STKE 2006 (316): pe1. doi:10.1126/stke.3162006pe1. PMID 16391178.
• Tellides G, Pober JS (2007). "Interferon-gamma axis in graft arteriosclerosis.". Circ. Res. 100 (5): 622–32. doi:10.1161/01.RES.0000258861.72279.29. PMID 17363708.

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